Handling Various Audio Sources from Archaic Media and Internet

In accumulating O-O-P music from various sources and migrating old recordings to iTunes, I needed to solve some technical issues discussed below.

My new iMac has digital ins and outs. I have an old A/V receiver (AVR) connected to these ports and providing a maze of connection possibilities via optical and coax digital connections. It also has dual-differential Burr-Brown (TI) converters, and thus is the DAC of choice for listening to music on the computer.

On the Mac, there are two places where the I/O routing from external devices is performed, in the OS X Audio Midi Utility, and in the preferences panel for whatever software will process the signal. Usually, these are set to the stereo digital in and out ports on the iMac. But they can also be pointed to an external multi-channel sound source, such as a FireWire audio I/F.

1. Copy DAT tape to iTunes

I input the digital stereo signal from the DAT player into the AVR, which gets forwarded to the computer. I capture the tape playback signal in CD Spin Doctor, an application distributed with Roxio’s Toast. Here I identify the start and end of the individual tracks manually via the displayed wave forms, aided by the track listing and times, and then have Spin Doctor do a direct import of the set of tracks into iTunes.

There were some computer DAT drives having firmware that will handle audio DAT as well as data DAT. They were configured in certain workstations from Silicon Graphics. Back when DAT was big, I bought such a used drive with thoughts of using it for computer input of DAT recordings, but before I got around to it, direct hard drive recording came on the scene and DAT faded into semi-obsolescence for audio recording purposes. But I still had a bunch of DAT recordings to input to iTunes.

2. Copy vinyl recordings to iTunes

This is similar to the above, except the digital input enters the computer via USB rather than S/PDIF. I play the vinyl on an inexpensive Audia-Technica USB turntable. The USB digital input goes directly into CD Spin Doctor. The alternative is to play the analog signal out of the turntable into an old pre-amp with phono input equalization, and then into the AVR, to use its high quality ADC chip. But the ADC in the USB output circuit sounds good enough, so I choose to keep it simple.

Vinyl introduces undesirable surface artifacts. CD Spin Doctor has click, crackle, and hiss filters that can be configured, but even the lightest filtering has a heavy-handed effect on the audio quality. So I search the waveform for audible discontinuities (pops) and connect the discontinuous samples graphically by hand using my Wacom Tablet. This is a highly localized operation that changes only a handful of samples involved in a pop. All but the most horrendous surface defects are neutralized by this approach, but it can be time consuming until one’s eye is trained to easily detect the waveform glitches. Poor quality vinyl would create a huge waste of time here, so I really only attempt this on pristine vinyl recordings for which no digital version was ever commercially produced.

3. Copy .flac files to iTunes

Sometimes one can find people on the Internet that have ripped O-O-P CDs and are willing to share their files. An open, cross-platform lossless-compressed format called flac is typically used. Roxio Toast itself is the big tool here. Open the Toast window in AudioCD mode and drag the .flac files onto the window. Then select the menu item to create a CD data file. Next select the menu option to mount the data file. iTunes will see the mounted file and will import the tracks just as if one were ripping a CD.

Internet file sharing has been greatly facilitated by the emergence of the cloud. Facilities such as Dropbox enable one post up files and then send a link to a potential user. Opening the link in ones browser causes the files to be downloaded.

4. Extract audio from You Tube videos into iTunes

Audience-recorded concert videos on the Internet have audio tracks unavailable in any other format. There are web sites that will accept links to You Tube videos and download the clips locally as .mp4 files. These video files can then be imported into Final Cut Express, from where the audio tracks can then be exported as .aiff files. If the video corresponds to a discrete track, this .aiff file can be imported directly by iTunes and converted internally to ALC format. Else, CD Spin Doctor can be used to import a .aiff file and separate it into discrete tracks as in (1) above.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s